Where should I go to make friends like me and maybe find someone to have a relationship with?

I have always had trouble getting out of the house. Ive never been proactive about making or keeping friends. Because of this I dont know a whole lot about making friends, adding my autism into the mix definitely doesn’t help. My problem is that im trying to find people not in the lets go party and get fucked up scene because thats really not for me. I like racing, star wars, legos, dnd, things like that. My other issue is that im 20 and a lot of things are 21+.

tldr: i know nothing about making friends and i want to make friend who are nerdy and enjoy the things i like.